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III. The physiological anatomy of the mouth-parts and alimentary canal of the Indian rat flea, Pulex cheopis, Rothschild

Published online by Cambridge University Press:  15 May 2009

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The key to the anatomy of the mouthparts of the flea and to the understanding of the mechanism of blood sucking is the recognition of the pricking epipharynx and of the hypopharynx with its salivary pumping apparatus. In general it may be stated that the epipharynx makes a way through the skin for the mandibles, that the mandibles enlarge and lacerate the hole thus bored and convey into it the salivary secretion which is pumped, by means of the salivary pump, down the salivary canal contained in them, and that the aspiratory pharynx aspirates blood from the now congested wound along the blood channel formed by the approximation of the epipharynx and the two mandibles. The whole complex of parts is adapted to form two channels, an effluent along which saliva is pumped down and an affluent along which blood is pumped up.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1906

References

page 487 note 1 Considerable difference of opinion has prevailed as to the true morphology of the appendage described as epipharynx. Landois in his classical memoir (Nova Acta Akad. Leop. Carol. 1867) employs the term “unpaariges Stechorgan” Karsten uses the term epipharynx; Gerstfeld and Grube (Arch. f. Naturgesch. 1854) on the contrary call it hypopharynx; Kraepelin (Ueber die system. Stellung der Puliciden, Hamburg, 1884) and more recently Heymons (Zool. Anzeiger, 1899) regard this organ as a true labium, “Oberlippe,” Jourdain (Bull. Soc. Entomol. de France, 1899, p. 294) has proposed the name syringostome, stating that it “est le prolongement même, en forme de bec tubule, de l'orifice buccal, et la lumière de ce prolongement est en continuité directe et interrompue avec la premiére part du tube digestif.” That this view is not correct will be seen on referring to the description above, the only lumen the “syringostome” possesses being in direct continuity with the hoemocoel. Wagner (Horae Soc. Entom. Rossicae, 1889–1903) states that it is a constant feature among the Aphaniptera for the walls of the “pricker” (epipharynx) to be prolonged laterally in the form of delicate chitinous lamellae which, interlocking with the mandibles, form with them a canal which he considers as the true sucking tube (“Saugrohr”) the cavity of the pricker he considers as the salivary excretory canal. It will be seen that Wagner is right in his designation of “Saugrohr,” but that his interpretation of the function of the pricker canal as a salivary canal is erroneous, the latter being situated in the mandibles.

Tiraboschi (Archives de Parasitologie, VIII. 1904, p. 214) will not accept the term “pricker” (piquant impair) and adopts that of tongue (langue). He states that the blunt form of the end and the presence on it of numerous small spinules directed forward would effectually prevent it being used as a pricking organ and considers it functions as a sucking tube. Here again the absence of any lumen within the organ communicating with the aspiratory pharynx effectually negatives this view.

page 489 note 1 Mouth. Tiraboschi describes the mouth as being situated at the antero-inferior margin of the head and as being bounded above by the maxillae and below by the labium; he is here describing what is designated in the text as the perioral ring.

page 489 note 2 Wagner describes the ducts as uniting just before entering the head, the single duct thus formed passing in the walls of the pharynx to become continuous with the cavity of the pricker. Kraepelin correctly describes and figures the salivary canals as situated in the mandibles.